Pressure method of working oil sands



July 30, 1929. L. RANNEY' 1,722,679

PRESSURE METHOD OF WORKING OIL SANDS Filed May 11, 1927 3 Sheets-Sheet I for} @Nj T July 30, 1929. RANNEY ,"1,

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' PRESSURE METHOD OF WORKING OIL SANDS Fild May 11, 1927 s Sheets-Sheet s Fla-4 OIL SAND OIL SAND L L i avwemtoz Zeo M W Patented July 30, 19219.

UNITED smrss 1,722,679 PATENT oFr cE- LEO RANNEY, OF NEW YORK, N. Y., ASSIGNOR TO STANDARD OIL DEVELOPMENT COMPANY, .A CORPORATION OF DELAWARE.

PRESSURE METHOD OF WORKING OIL SANDS.

Application filed May 11,

This invention relates to improvements in the recovery of oil from the earth by mining methods of the type described and claimed in my United States Patents Nos. 1,634,235 and 1,634,236, granted June 28, 1927, and in my copending'application Serial No. 100,531, filed April 8, 1926.

In the method described in those patents and application, a mine gallery is driven adjacent the oil sand but spaced therefrom by material. substantially impervious to fluid. The gallery may be above or below the sand. Holes forming mine wells are drilled from the gallery into the oil sand. Nipples sealed in the mine wells receive the oil or other fluid and discharge it into collecting pipes. Valves are provided on each nipple for the control of flow.

The invention will be fully understood from the following description read in connection with the accompanying drawings, in

which Fig. 1 is a diagrammatic vertical section through an installation embodying the invention;

Fig. 2 is a diagrammatic transverse section showing an arrangement of the mine wells about the producing area;

Fig. 3 is a vertical section on the line III-III, Fig. 2; and

Fig. 4 is a diagrammatic vertical section showing air or gas lift means.

Referring first to Figs. 1 and 2, reference numeral 1 denotes a mine shaft opening into a mine gallery 2. This gallery is formed in a lower cap rock 3 underlying an oil sand 4. The shaft 1 is surrounded by a concrete wall 5,011 the like, where it passes through the oil sand. A collecting pipe 6 is installed in the gallery 2 and is connected by cross fittings 7 to a large number of closely spaced nipples 8. These nipples are sealed in the cap rock, as at 8'. They are directed toward the oil sand but do not enter it, unless it is necessary to have the nipples extend above the level of any water that may be in tht bottom of the sand. A gate valve 9 and pressure gage 9 are provided on each nipple.

A hole 10 is drilled from the end of each nipple into the oil sand, forming mine wells. The procedure,- as described in my patents and application mentioned above, is to seal the nipple in place, remove a plug 11 on the bottom arm of the cross fitting 7, insert the drill through a stufling box (not shown) 1927. Serial No. 190,393.

attached at the lower end of the cross fitting, open the gate valve, insert the drill through the nipple and through the open gate valve, and drill int-o the sand. When this has been done, the drill is drawn back past the gate valve, which is then closed. The drill and stufiing box can now be removed and the plug 11 replaced without danger of fluids escaping from the sand into the gallery- The collecting pipe 6 discharges into a separator 12 in which bafile plates 13 are arranged. Gas is vented from the separator through a pipe 14. Oil is withdrawn by a pump 15 through a pipe 16 to an aboveground storage tank 17. A pipe 18 is provided for removing water that may collect in the lower part of the separator.

Test pipes 19 extend into the oil sand to a progressively increasing distance from the gallery. Each test pipe has a pressure gage 20, and a draw-oil valve 21 for sampling the contents of the pipe. Thermometers or any other desired measuring or recording instruments may be connected to or inserted into the test pipes.

One or more wells 22 are drilled from the surface of the earth to the upper part of the oil sand. A compressor 23 is provided for forcing natural gas, natural gas saturated with gasoline vapor, air, or other oilexpelling fluid through these wells into the sand. In cases where the sand is of substantially uniform porosity throughout, I prefer to utilize one centrally located surface well 22, as shown in Fig. 2. When working a square tract of 40 acres, a gallery 2 may be driven-completely around the tract with closely spaced mine wells formed from the gallery. There may be 132 of these mine wells on each side of the tract. 5 A smaller number will do for very porous sands. Various other arrangements of the galleries, injection wells, and mine wells may be made.

The injected natural gas or other oil-ex- 100 pelling agent causes the oil to flow toward, the mine wells located around the field. In the absence of gas pressure, oil does not flow as completely as is desirable to the collecting wells.- Apparently, it is retained in the 105 central part of the area at a higher level than at the edges, the surface of oil-saturated sand sloping from the center downward to the mine wells, as at S, Fig. 3. This may be referred to as the angle of 110 repose of oil in the sand. The injected gas tends to flatten this angle and in its radial movement from the intake well drives oil towards the mine wells.

In case there are dense portions of the sand, it may benecessary to distribute surface wells so as to avoid the blocking off of the injected gas. One or more surface wells may be drilled on each side of the dense portions, so that the injected gas may have access to all the sand.

The following example will show how the installation is operated It will be understood that the present invention is designed primarily for recovering oil from those low ressure sands which are exhausted so ar as surface well production is concerned, but which nevertheless contain much oil. An expulsive agent, for example natural gas, is forced into the central well 22 ata pressure of about 100 lbs. per square inch. This pressure gives adequate flow in oil sands of. ordinary compactness. When a high rate of oil flow is desired, or when the sand is very dense,"the pressure may be 200 lbs. or more per square inch. On the other hand, pressures as low as 20 lbs. per square inch are satisfactory for very porous sands and a medium rate of oil flow. The pressure is determined by natural and economic conditions. v

The preferred procedure is to maintain a horizontal layer of oil-saturated sand, forming a barrier between the expulsive agent and any exit from the sand. This is an important feature of the invention. In surace well practice,gas injected into the sand is not fully efiective. Both the gas intake wells and the oil producing wells extend through the entire body of sand, so that at.

any level in the intake-wells there is an opening through any porous streaks in the sand to the same level in the producing wells. These porous streaks normally run horizontally, parallel to the body of sand, and serve as conduits for the gas, which accordlngly escapes without exerting much pressure u on the oil. Such porous streaks,

' although lled with oil, donot constitute a barrier. The injected gas easily displaces the oil, since the movement is horizontal. Oil moves rather readily in this. direction.

In my method the oil movement may be compelled transversely downward. Oil resists flow in this direction and furnishes an excellent surface for the application of the gas pressure. The impervious barrier of 011 may be gradually forced down toward the collecting wells, with a very high re cpvery of oil. In addition to the protect1on against escape of gas afforded by the horizontal layer of sand filled with oil, a furthenprotection is provided by maintainng periodlcally as required a column of oil in each nipple, above the valve but not high down until only oil is produced. It will be understood that this blowing through of gas may be permitted to occur periodically for short intervals, with resulting temporary evacuation of the adjacent region in the sand, the valves then being regulated to' check the escape of gas.

The pressure of the injected gas is regulatcd so as to control the tendency of the gas to break through at the mine wells. To this end I have provided groups of test pipes 19 at various places in the gallery. The pressure differential between the gas-filled space in the sand andthe point of withdrawal of oil from the sand may be determined by consulting the pressure gages 9 and 20 on the oil collecting nipples 8 and the test pipes 19, respectively. If the proper pressure differential is maintained, there'will be a constant and regular flow of oil from the exposed sand in the mine wells, without the uncontrolled escape of the expulsive gas. For example, if in a sand of a certain porosity it is found that a differential of 5 lbs. is most effective for the expulsion of oil, this differential is maintained as closely as possible. If the differential becomes less than 5 lbs., the control valve 9 on the nipple 8 is slightly restricted, and if the differential becomes more than 5 lbs., the control valve is slightly released.

In Fig. 4 there is illustrated an alternative form of installation in which a gallery 24 is driven in a cap rock 25 overlying an oil sand 26. An oil collecting pipe 27 is laid in the gallery and is connected to a plurality of nipples 28, only one of which is shown. The nipple 28 is sealed in the cap rock by sealing material 28' and extends downward tonearthe bottom .of the sand.-

A gas or air line 29 is installed in the gallery and has a branch 30 passing through the nipple and beyond its lower end.

The gas pressure imposed on the sand through the surface well 22 cannot be economically used to raise the oil when the sand is of considerable thickness. In such acase the column of oil standing in the collecting nipple 28 may have sufficient hydrostatic,

head to exert an objectionable back pressure on the sand, preventing or retarding the flow of oil. When this occurs, gas is passed through the line 29 and branch 30. It will bubble up through the oil in the nipple, lighteningit and causing it to overflow into the collecting pipe '27. To prevent the return of any oil to the nipple, an inverted goose neck 31 is formed at the joint where each nipple joins the collecting pipe 27. Oil may be raised in this way without objectionable back pressure on the sand. In the average case, an air lift can be operated in the manner described with the exertion of less than one atmosphere gauge pressure against the exposed face of the oil sand.

When the sand is not very thick, oil can be raised to the collecting system by the application of a small amount of pressure,

without the aid of a. gas lift. Thus the oil may not have to rise more'than a fewfeet in nipple 30 (Fig. 4), before discharging into the collecting system 27. A pressure which would be quite incapable of forcing the oil to the surface of the earth will easily suifice to raise the oil tothe collecting system.

Pressure gages 32 and 33- are provided on the pipes 27 and 29. A pressure gage 34 is also connected directly with the to of the sand so thatthe pressure in it may be ascertained. Samples of gas may be taken off i for analysis through the valved pipe Control valves 36 and 37 are arranged 1n pines 27 and 29.

In some cases it may be desirable to utilize expulsive agents heavier than oil, such as water or acqueous salt solutions. Water,

for example, can be run in through one or more surface wells to a point adjacent the bottom of ,the oil sand. I Mine wells, formed from above the sand, as described in connection with Fig. 4, receive the -oil forced upward by the water rising horizontally through the sand. In this mode of applying the invention there is a barrier of oil filled sand above the explusive agent; in the gas method previously described such a barrier is below the expulsive agent. The

water, like the gas, can be controlled in its escape along any level through porous streaks to producing wells, and may be compelled to move across the oil bearing stratum.

An auxiliary barrier against escape of expulsive agent (air, gas, water, etc.) may be provided by maintaining a column of oil in each downwardly extending nipple 28, said column preferably being in contact with the valve in the nipple. The control valves in the nipples are adjusted to secure this result, the method being analogous to that described above for retaining oil in the upwardly extending nipples 8.

Various changes and alternative arrangements may be made within the scope of the appended claims, in which it is my intention to claim all novelty inherent in the invention as broadly as the prior art permits.

I claim:

1. In the recovery of oil from an oil hearing stratum by a mining method, the improvement which comprises forcing an oil expulsive agent into the stratum near an outside surface only, and withdrawing oil from points only opposite said surface, whereby the expulsive agent is compelled to move transversely across the stratum and to force the oil toward the points of withdrawal. v

2. In the recovery of oil from an oil-bearing stratum by a mining method, the improvement which comprises forcing an oil expulsive agent into the stratum near an outside surface only, withdrawing oil from points only opposite said surface, whereby the expulsive agent is compelled to move transveresly across the stratum and to force the oil toward the points of withdrawal, and controlling the escape of the expulsive agent.

3. Method accordin to claim 2, in which gas escapes through the oil withdrawal lines and control means is then actuated to check the escape of gas.

4. In the recovery of oil from an oil bearing stratum by a mining method, the improvement which comprises forcing an oil expulsive agent into the upper part of said 5. Method according to claim 4, in which the pressures in the various areas of the oilbearing stratum are determined, and the flow openings are controlled in accordance with the pressures to prevent the expulsive agent from breaking through at any of said openings.

6. In the recovery of oil from an oil sandby a mining method, the improvement which comprises forcing a gas into the sand near its upper surface, withdrawing oil from a plurality of points adjacent the bottom only of the sand, and so regulating the pressure and withdrawal of oil as to maintain at all times a barrier of oil-filled sand between the gas-filled area and the withdrawal openings.

7. In the recovery of oil from an oil sand by a mining method, the improvement which comprises forcing a gas into the sand near its upper surface, withdrawing oil from a plurality of closely spaced points adjacent the bottom only of the sand, determining the pressures prevailing in various areas of the sand, and regulating the pressure of the gas and the withdrawal of oil to maintain a proper pressure difl'erential between the gas in the sand and at the exposed producing surface.

8. In the recovery of oil from an oil sand by a mining method, the improvement which comprises forming a plurality of openings around the area of sand to be worked, said of oil from near the bottom bf the sand, forcinga gasinto the sand near its upper surface and within said area, preventing escape of said gas, and withdrawing oil from said openings. I

- 9. In the recovery of oil from'an oil sand by a mining method, the improvement which comprises driving a gallery above the sand,

said gallery being adjacent the sand but spaced therefrom by material impervious to fluids, drilling from the gallery to form a plurality of mine wells 'opening near the bottom ofthe sand, injecting a gas into the upper part of the sand to force the oil toward the mine wells, and applying fluidlift means to raise the oil insaid wells.

10. In the recovery of oil from an oil bearing stratum by a mining method, the improvement which comprises forcing an.o1 l

expulsive agent into the stratum near itsupper surface only, forming a plurality of oil withdrawal openings in the lower part only of the stratum, seating valved nipples in said openings, and regulating the flow through the nipples to retain a suflicient column of oil' above the valves therein tov prevent passage of expulsive agent through the nipples. 7

11 In the recovery of oil-from an oil bearing stratum by a mining method, the improvement which comprises forcing an expulsive agent into the stratum near its upper surface only, forming a large number of closely spaced oil withdrawal openings in the lower part only of the stratum, whereby the expulsive agent is compelled to move downwardly against a receding barrier of oil, seating valved nipples in said openings, and retaining a column of oil in any nipple above the valve therein when the expulsive agent approaches said nipple, whereby a further I l barrier to the escape of the expulsive agent is provided.

12. In the recovery. of oil from an oil. sand by a mining method, the improvement which comprises establishing a point of withdrawal of oil near the bottom of the oil sand, forcing a pressure medium into the 'uppen part of the sand, and delivering said withdrawn oil at a short distance only above the sand into a collecting system whereby a medium of relatively low pressure is capable of lifting the oilinto the collecting system.

14. An oil recoverfy installation comprising amine gallery 1 ormed adjacent an oil I sand but spaced therefrom by material sub stantially impervious to fluids, an oil collecting pipe in said gallery and connected at a plurality of points with the bottom only of the oil sand, a separator into which said collecting pipe discharges, means for forwarding separated oil and gas'to the surface of the earth, a surface well extending into the upper part ofthe oil sand, means for forcing an oil expelling gas through said Well into the sand, and means for determining the pressures prevailing in the gas filled area of the sand and at the points of withdrawal of oil therefrom.

LEO RANNEY. 

